Method of developing latent electrostatic images

ABSTRACT

A LATENT ELECTROSTATIC IMAGE ON A SURFACE OF A CARRIER IS DEVELOPED INTO A VISIBLE IMAGE BY MOVING THE CARRIER ALONG A DEVELOPING PATH WITH THE IMAGE-BEARING SURFACE CONTACTING A DEVELOPING LIQUID IN EFFECTIVE FIELD CONTROL SPACING WITH AN ELECTRICALLY CONDUCTIVE SURFACE OF AN IMAGE INTENSIFIER MOVING ALONG THE DEVELOPING PATH. DEVELOPING LIQUID IS SUPPLIED TO THE SURFACE OF THE IMAGE INTENSIFIER BY A POROUS WIPER WETTED WITH DEVELOPING LIQUID, AND AN INCOMING IMAGE-BEARING CARRIER IS GUIDED ALONG THE DEVELOPING PATH IN CONTACT WITH THE DEVELOPING LIQUID BY RIDGES EXTENDING ALONG THE DEVELOPING PATH ON AN UPWARDLY CONCAVE WALL WHICH FORMS A TROUGH THROUGH WHICH THE IMAGE INTENSIFIER MOVES. AS THE CARRIER MOVES THROUGH THE DEVELOPING TROUGH, THE IMAGE-BEARING SURFACE IS PRESSED INTO EFFECTIVE FIELD CONTROL SPACING WITH THE IMAGE INTENSIFIER OVER AN ELONGATED DISTANCE OF THE DEVELOPING PATH BY DEVELOPING LIQUID WHICH IS RECEIVED INTO A CHAMBER AND DIRECTED AGAINST THE BACK SIDE OF THE CARRIER BY ORIFICES FORMED IN THE UPWARDLY CONCAVE WALL. AFTER PASSING THROUGH THE TROUGH, THE CARRIER IS GUIDED THROUGH A PAIR OF COOPERATING SQUEEGEE ROLLERS WHICH REMOVE EXCESS DEVELOPING LIQUID FROM THE CARRIER.

June 6, 1972 G. J. MILLER 3,667,987

METHOD OF DEVELOPING LATENT ELECTROSTATIC IMAGES Filed Dc. 12, 1969 4Sheets-Sheet 1 INVENT OR ATTORNEYS GEORGE 3'. VHLLEK v G. J. MILLER3,667,987

METHOD OF DEVELOPING LATENT ELECTROSTATIC IMAGES Filed Dec. 12, 1969June 6, 1972 4 Sheets-Sheet 2 83 I g A i June 6, 1972 J,'MILI ER3,667,987

METHOD OF DEVELOPING LATENT ELECTROSTATIC IMAGES Filed Dec. 12, 1 969 4Sheets-Sheet 5 W INVENTOR GEORGE J'. MILLER A ORNEES' June 6, 1972 G. J.MILLER METHOD OF DEVELOPING LATENT ELECTROSTATIC IMAGES 4 Sheets-Sheet4.

Filed Dec. 12, 1969 "fi l lWI l l I INVENTOR GEORGE 3'] MI LLEKATTORNEYS United States Patent Office 3,667,987 Patented June 6, 1972US. Cl. 117-37 LE 6 Claims ABSTRACT OF THE DISCLOSURE A latentelectrostatic image on a surface of a carrier is developed into avisible image by moving the carrier along a developing path with theimage-bearing surface contacting a developing liquid in effective fieldcontrol spacing with an electrically conductive surface of an imageintensifier moving along the developing path. Developing liquid issupplied to the surface of the image intensifier by a porous wiperwetted with developing liquid, and an incoming image-bearing carrier isguided along the developing path in contact with the developing liquidby ridges extending along the developing path on an upwardly concavewall which forms a trough through which the image intensifier moves. Asthe carrier moves through the developing trough, the image-bearingsurface is pressed into effective field control spacing with the imageintensifier over an elongated distance of the developing path bydeveloping liquid which is received into a chamber and directed againstthe back side of the carrier by orifices formed in the upwardly concavewall. After passing through the trough, the carrier is guided through apair of cooperating squeegee rollers which remove excess developingliquid from the carrier.

This invention relates to a developing station for an electrostaticphotocopying machine, and more particularly to a developing stationwherein a latent electrostatic image on a surface of a carrier isdeveloped into a visible image by bringing the image-bearing surface ofthe carrier into contact with a developing liquid in effective fieldcontrol spacing with an electrically conductive surface.

In an electrostatic photocopying machine, a copy of a document isproduced by forming a latent electrostatic image of the document on thesurface of a suitable carrier, for example a sheet of copy paper, andthen developing the latent image into a visible image. The latent imageis developed into a visible image by bringing the imagebearing surfaceof the copy paper into contact with a developing liquid having visibleparticles which are electrically attractable to the electrostatic image.The visible developer particles are attracted by the portions of theimage-bearing surface having an electrostatic charge and are depositedthereon to transform the latent image into a visible image.Subsequently, the image-bearing carrier is passed between a pair ofsqueezee rollers which remove excess liquid from the carrier and pressthe visible particles forming the developed image into the image-bearingsurface.

During the development of a latent electrostatic image, the visibledeveloper particles often tend to be deposited more densely along thefringe portions of the image as compared to the central portionsthereof, and this effect is usually referred to as fringe development.When the visible developer particles are attracted to the latentelectrostatic image, they move in an electrostatic field produced by thelatent electrostatic image. The electrostatic field is theoreticallycomposed of lines of force, and the phenomenon of fringe development isbelieved to result from the lines of force being more concentrated atthe fringe portions of the image, thus causing the developed particlesto be more strongly attracted thereto as compared with the centralportion of the image.

It is known that the fringe effect may be alleviated to produce a moreuniform development of the latent image by bringing the image-bearingsurface of the carrier into close proximity with an electricallyconductive surface so as to straighten out the lines of force and thusreduce the concentration of the lines of force at the fringe portion ofthe image. However, several problems are encountered in bringing theimage-bearing surface of the carrier into close proximity with theelectrically conductive surface of an image intensifier. If theimage-bearing surface is brought too close to the surface of the imageintensifier, then there may be insuflicient visible particles in theintervening space to fully develop the latent image. On the other hand,if the intervening space is too great, then the image intensifier willnot be effective in straightening out the lines of force and producing amore uniform development of the latent electrostatic image. Furthermore,to enhance the effect of the image intensifier, it is desirable tomaximize the period of time that the image-bearing surface is ineffective field control spacing with the image intensifier.

In the past, there have been developing stations which bring animage-bearing carrier into effective field control spacing with an imageintensifier in the presence of a liquid developer. However, suchdeveloping stations usually have a mechanical apparatus which contactsthe imagebearing carrier while bringing it into effective field controlspacing with the image intensifier, and the use of such a mechanicalapparatus generally increases the difficulty in assembling thedeveloping station as well as increasing the cost of the photocopyingmachine. Furthermore, such an arrangement usually has stationarysurfaces which are contacted by the image-bearing carrier as it isbrought into effective field control spacing with the image intensifier,and this often results in scuff marks being placed on the carrier due tocontact with visible particles which may have accumulated on thestationary surfaces.

Accordingly, an object of the present invention is to provide uniformdevelopment of a latent electrostatic image by bringing it intoeffective field control spacing with an image intensifier without theuse of a mechanical apparatus for pressing the carrier into closeproximity with the image intensifier.

Another object of the present invention is to provide a developingstation for bringing an image-bearing surface of a carrier intoeffective field control spacing with an image intensifier withoutplacing undesirable scuff marks on the back of the carrier as it movesthrough the developing station.

A further object of the present invention is to provide a developingstation for uniform development of a latent electrostatic image, whereinthe developing station may be easily assembled with a minimum number ofparts, and particularly without the need of a mechanical apparatus forbringing the image-bearing surface of the carrier into effective fieldcontrol spacing with an image intensifier.

Still other objects, features and advantages of the present inventionwill be apparent tothose skilled in the art from a reading of thefollowing detailed description of the various embodiments of theinvention, taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of a preferred embodiment of a developingstation according to the present invention;

FIG. 2 is a partial cross-sectional view of the developing station shownin FIG. 1, and illustrating an incoming image-bearing carrier movinginto the developing trough;

FIG. 3 is a partial cross-sectional view of the developing station shownin FIG. 1, and illustrating an image-bearing carrier moving into apressurized area of the developing station;

FIG. 4 is a partial axial cross-sectional view of the developing stationshown in FIG. 1, with the developing station being supported between twoupright walls;

FIG. 5 is a plan view of the developing trough shown in FIG. 1;.

FIG. 6 is a side view of an alternative developing station constructedin accordance with the present invention, and illustrating the movementof an image-bearing carrier therethrough; and

FIG. 7 is a cross-sectional view of the embodiment shown in FIG. 6,taken along the lines 77.

Referring generally to FIGS. 1-5 in the drawings, there is shown adeveloping station, generally indicated 11, for developing a latentelectrostatic image on a surface 13 of a carrier 15 into a visible imageas the carrier 15 moves past the developing station 11 along adeveloping path. The incoming image-bearing carrier 15 is guided into atrough 17 and brought into contact with developing liquid 19 on anelectrically conductive surface 21 of a cylinder 23 rotating in thetrough 17. As the carrier 15 moves through the trough 17, it enters apressurized area, generally indicated 25, where additional developingliquid 19 is directed under pressure against the back side of thecarrier 15 to press the image-bearing surface 13 into effective fieldcontrol spacing with the electrically conductive surface 21 of thecylinder 23. The pressurized area 25 extends over an elongated distanceof the developing path, and the cylinder 23 serves as an imageintensifier to straighten out the lines of force produced by theelectrostatic image to achieve a more uniform deposition of visibleparticles on areas of the image-bearing surface 13 having the sameuniform electrostatic charge. From the trough 17, the image-bearingcarrier 15 passes between the cooperating surfaces of a pair of rotatingsqueegee rollers 27, 29 respectively, which remove excess developingliquid from the carrier 15 and press the visible particles into thesurface thereof to provide a permanent copy of an original document.

The developing station 11 is supported in the photocopying machine bytwo parallel upright walls 31, 33 and positioned to receive a carrier 15being advanced by a suitable transport mechanism, generally indicated35, and subsequently direct the carrier 15 into the nip of thecooperating squeegee rollers 27, 29 which remove the carrier 15 from thedeveloping station 11 for further processing in the machine. As moreparticularly shown in FIG. 2, an incoming carrier 15 is received intothe developing trough 17 beneath the image intensifying cylinder 23which is rotatably supported for movement about an axial shaft 37 havingreduced end portions 39, 41. As shown in FIG. 4, the reduced end portion39 is received through a suitable bushing 43 which is secured in anopening 45 formed in the upright wall 31. The other reduced end portion41 is rotatably supported in the same identical manner and accordinglyidentical reference numerals have been placed on identical portions.

The lower portion of the cylinder 23 extends into the trough 17 which isdefined by a generally upwardly concave wall 47 formed integrally withspaced side walls 49, 51 respectively, which are located beside theopposite ends of the cylinder 23. An incoming carrier 15 is guidedthrough the trough 17 and around the image intensifying cylinder 23 byguide means, generally indicated 53, which are provided on the bottomwall 47 of the trough 17. As more particularly shown in FIG. 5, theguide means 53 are in the form of ridges 54 extending along the developing path obliquely to the direction of movement of a carrier 15 alongthe path. The guide means 53 are easily positioned relative to thesurface 21 of the cylinder 23 during the assembly of the developingstation 11 by providing each of the side walls 49, 51 of the trough 17with a raised portion 55 having a V-shaped groove 57 for engaging theaxial shaft 37 of the cylinder 23. The trough 17 may be fixedly securedby suitable means between the upright walls 31, 3-3.

The image intensifying cylinder 23 may be constructed from a suitableelectrically conductive material, such as steel or aluminum.Alternatively, the cylinder 23 may be formed from an electricallyinsulating material, and then coated with a suitable electricallyconductive material. The trough 17 may be constructed from a suitableelectrically insulating material which is not affected by the developingliquid 19, and which does not adversely affect the developing liquid 19.One such material is acrylonitrile-butadienestyrene copolymer. Thebushings 43 which receive the reduced end portions 39, 41 of the axialshaft 37 may be constructed from a suitable electrically conductingmaterial, for example bronze.

As shown, the paper transport mechanism 35 may be a conventional endlessbelt 61 trained around a suitable roller 63 which may be rotatablysupported between the two upright walls 31, 33 in the same manner as thecylinder 23. A carrier 15 transported along the endless belt 61 may beguided into the developing station 11 by another rotatably supported andcooperating idler roller 65 which engages the image-bearing surface 13of the carrier 15 and is positioned relative to the roller 63 fordirecting the carrier 15 into the developing trough 17 beneath thecylinder 23. The endless belt 61 may be constructed from a suitablematerial, for example rubber, and the cooperating roller 65 is providedwith an electrically insulating surface, by means of a rubber sleeve 67,to enable it to contact the image-bearing surface 13 of the carrier 15without discharging the latent electrostatic image.

As previously mentioned, the cooperating squeegeeing rollers 27, 29remove excess developing liquid from the carrier 15 and press thevisible particles into the imagebearing surface 13. The cooperatingsqueegee rollers 27, 29 may be rotatably supported between the twoupright walls 31, 33 in the same manner as the cylinder 23, with theroller 29 engaging the back side of the image-bearing carrier 15 whilethe roller 27 engages the image-bearing surface 13. The roller 29 is anidler roller having a sleeve 69 constructed from a resilient material,such as rubber, while the roller 27 is a drive roller which pressesagainst the resilient sleeve 69 of the idler roller 29. The drive roller27 is constructed from a suitable electrically conductive material, suchas steel, and may desirably be pressed against the idler roller 29 by aconventional resilient biasing means, not shown.

The electrically conductive surface 21 of the image intensifyingcylinder 23 and the electrically conductive squeegee roller 27 may bothbe electrically grounded by suitable means, for example through bushingsor a brush contact, to the frame portions of the photocopying machine,for example the parallel upright Walls 31, 33. In addition, the imageintensifying cylinder 23, the roller 63 for the endless transport belt61, and the squeegee roller 27 may all be separately driven byconventional drive means, not shown, or for that matter may be driven bya common drive means through a conventional chain and sprocketarrangement.

As the cylinder 23 rotates in the developing trough 17, developingliquid, generally indicated at 19, is supplied from a suitablereservoir, not shown, onto the surface 21 of the cylinder 23 by [fluidsupply means, generally indicated at 71. As shown, the fluid supplymeans 71 is in the form of an apertured header tube 73 which extendsacross the length of the cylinder 23 above a wiper 75 engaging the uppersurface portion of the rotating cylinder 23. The wiper 75 is constructedfrom a suitable porous material, such as an open-celled polyurethanefoam. The wiper 75 is held against the surface of the cylinder by asuitable clamp 77 which may be supported between the two up right walls31, 33 and a shield 79 which protects other portions of the photocopyingmachine, not shown, from becoming wetted with the developing liquid 19.To insure thorough saturation of the wiper 75 by the developing liquid19, the header tube 73 directs the developing liquid '19 onto the shield79 so as to form a pool of developing liquid between the shield 79 andthe wiper 75. In addition, developing liquid is supplied under pressureto the bottom portion of the trough 17 in the pressurized area 25 in amanner which will be described hereinbelow.

The developing liquid 19 supplied to the developing station 11 fills thetrough 17 and flows over recesses 81 formed in the bottom wall 47 besidethe side walls 49, 51 and into a gutter, generally indicated 83. Thegutter 83 surrounds the developing trough 17 and carries the developerliquid 19 to a sump 85 where it drains back to the reservoir. As shown,the gutter 83 may be formed integrally with the trough 17, oralternatively may be formed separately and secured in fluid-sealingrelation to the trough 17. The means for circulating the developingliquid 19 between the reservoir and the developing station 11 have beenomitted from the description, since it forms no part of the presentinvention.

When an incoming image-bearing carrier 15 is advanced into thedeveloping station 11, by the transport mechanism 35, the leading edgeof the carrier 15 is guided by the guide means 53 into the developingliquid 19 in the space between the upwardly concave wall 47 and therotating cylinder 23. As the incoming carrier 15 moves further along thedeveloping path, the ridges 54 guide the image-bearing surface 13 of thecarrier 15 into substantially constant spaced relation with the surface21 of the cylinder 23. As more particularly shown in FIG. 5, the ridges54 are generally oblique to the direction of movement of the carrier 15,and it is believed that the movement of the back side of the carrier 15across the oblique ridges 54 provides a wiping action which prevents anaccumulation of visible developer particles on the ridges 54 andprevents backmarking of the carrier 15. In addition, the ridges 54 serveto reduce the friction the carrier 15 would otherwise encounter if itmoved along a that bottom wall.

[Further advancement of the carrier 15 along the developing path bringsthe leading edge into the pressurized area 25 where developing liquid isdirected under pressure toward the surface 21 of the rotating cylinder23. As more particularly shown in FIGS. 24, developing liquid 19 isreceived into the pressure chamber, generally indicated 87, through apassageway, generally indicated 89. The passageway 89 opens into thechamber 87 adjacent a baffie wall 91 at the center thereof so as toenable the fluid to be evenly distributed throughout the chamber 87,From the ifluid pressure chamber 87, the fluid flows into the bottomportion of the trough 17 through orifices, generally indicated 93, whichare formed in the upwardly concave wall 47 so as to direct thedeveloping liquid toward the surface 21 of the rotating cylinder 23. Asshown, the pressure chamber 87 is formed by a generally box-shaped wall95 depending integrally from the back side of the upwardly concave wall47, and which is closed by a manifold cap 97 engaging the dependingbox-shaped wall 95 in fluid-sealing relation thereto. The passageway 87is defined by a portion of the wall 95 and a wall '88 extending adjacentthereto. The wall 88 may be formed integrally with the upwardly concavewall 47.

The pressurized area 25 extends over an elongated distance of thedeveloping path generally adjacent the orifices 93 in the bottom wall 47of the developing trough 17. As more particularly shown in FIG. 5, theorifices 93 in the upwardly concave wall 47 are arranged in dual rowstransverse to the direction of movement of the carrier 15. When thecarrier 15 enters the pressurized area 25, the developing liquid 19directed towards the cylinder 23 tends to press the leading edge of thecarrier 15 away from the surface 21 of the cylinder 23. However, theridges 54 maintain the image-bearing surface 13 in substantiallyconstant spaced relation with the surface 21 of the cylinder 23 until aSUfilClCIlt length of the incoming carrier 15 enters the pressurizedarea 25 to enable the force of the liquid 19 to lift the carrier 15 fromthe ridges 54 and press the image-bearing surface 13 into effectivefield control spacing with the image intensifying cylinder 23. Althoughthe means for circulating the developing liquid from the reservoir tothe pressurized area 25 are not shown, the effective field controlspacing may be varied by controlling the pressure of the developingliquid directed against the back side of the carrier 15.

As the carrier 15 moves through the pressurized area 25, theimage-bearing surface 13 is maintained in substantially constant spacedrelation with the image intensifier roller 23 the length of theelongated distance of pressurized area 25 is extended along thedeveloping path so as to maximize the period of time that the carrier 15is in effective field control spacing and thus enhance the deposition ofvisible particles onto the image-bearing surface 13. It is believed thatthe electrically conductive surface 21 of the cylinder 23 serves tostraighten out the lines of force of the electrostatic field produced bythe latent electrostatic image. As a result, the visible particles inthe developing liquid 19 confined in the effective field control spacingbetween the image-bearing surface 13 of the carrier 15 and theelectrically conductive surface 25 of the image intensifying cylinder 23are more uniformly deposited on areas of the latent image having thesame uniform electrostatic charge. In addition, it is believed that thedeveloping liquid 19 directed against the back side of the carrier 15tends to wash the back side of the carrier 15 free from visibledeveloper particles which may be placed there during the course ofmovement along the ridges 54.

From the pressurized area 25, the image-bearing carrier 15 is guidedinto the nip of the cooperating squeegee rollers 27, 29 which arerotatably driven so as to have a peripheral speed substantially equal tothe linear speed of the image-bearing carrier 15. As the carrier 15passes between the squeegee rollers 27, 29 the electrically conductivesurface of the roller 27 presses the carrier against the rubber sleeve69 on the roller 29 so as to produce a squeegeeing effect which removesexcess developing liquid 19 from the carrier 15 and presses the visibleparticles of the developed image into the image-bearing surface 13. Toprevent over-printing resulting from developer particles clinging to theelectrically conductive surface of the roller 29, the wiper 75 is alsoheld against the surface of the squeegee roller 29 so as to wipe thesurface free from any visible developer particles.

Another embodiment of a developing station constructed in accordancewith the present invention is shown diagramatically in FIGS. 6 and 7.With the exception of the image intensifier, the developing station,generally indicated 11', of this embodiment is generally identical tothe developing station 11 described in the previous embodiment, andaccordingly identical reference numerals have been placed on identicalportions thereof. In this embodiment, the image intensifier is in theform of an endless belt 99 having an electrically conductive surface 101which is movable along the developing path. The image intensifying belt99 extends around two rotatable rollers 103, 105 which are spacedsufficiently apart to maintain the belt 99 in a taut condition. Thelower portion of the image intensifying belt 99 moves through thedeveloping trough 17 which is formed by a generally upwardly concavebottom wall 47 extending in a linear direction over an elongateddistance of the developing path so as to increase the elongated lengthof the pressurized area 25 of the developing station 11.

The rollers 103, 105 for the image intensifying belt 99 may be rotatablysupported between the upright walls 31, 33 in the same manner as theimage intensifying cylinder 23 of the previous embodiment, and eitherroller may be rotatably driven to move the belt 99 by means offrictional engagement through the developing trough 89' is defined bytwo walls 88', 90' which may be formed integrally with the generallyupwardly concave bottom wall 47. Also, since the fluid supply means islocated further from the paper transport 35 than in the previousembodiment, it is unnecessary to provide a shield to prevent othercomponents of the machine from being wetted by the developing liquid 19.Accordingly, the header tube 73 is turned so that the developing liquid19 is directed onto the wiper 75 rather than against the shield, as inthe previous embodiment.

In operation, an, image-bearing carrier is advanced by the papertransport apparatus 35 into the developing station 11' where the leadingedge of the carrier 15 is guided by the guide means 53 into thedeveloping trough 17 beneath the image intensifying belt 99. As theincoming carrier 15 moves along the developing path, the ridges 54 guidethe image-bearing surface 13 of the carrier 15 into substantiallyconstant spaced relation with the surface surface 13 having the sameuniform electrostatic charge.

After moving through the pressurized area, the imagebearing carrier 15is guided into the nip of the rotatably driven squeegee rollers 27, 29which remove excess developing liquid 19 from the carrier 15 and pressthe visible particles of the developed image into the image-bearingsurface 13 to provide a permanent copy of the original document.

While only a limited number of embodiments have i been illustrated anddescribed, it will be apparent to those skilled in the art that variousmodifications and improvements may be made without departing from thescope and spirit of the invention. Accordingly, it is to be understoodthat the invention is not to be limited by the illustrative embodiments,but only by the scope of the appended claims.

What is claimed is:

1. A method of developing a latent electrostatic image on a surface of acarrier, comprising the steps of wetting an electricallyconductive-surface with a developing liquid, moving the wetted surfacealong a developing path, moving a carrier having a latent electrostaticimage on a surface thereof along the developing path with theimagebearing surface of the carrier in contact with the developingliquid on the moving electrically conductive surface, and applyingdeveloping liquid under pressure to the carrier over anelongateddistance of the developing path to press the electrostaticimage-bearing surface of the carrier into an effective field controlspacing with the electrically conductive surface over the elongateddistance of the developing path, said carrier and said conductivesurface moving in the same direction.

2. A method of developing a latent electrostatic image on the surface ofa carrier according to claim 1, wherein said image-bearing carrier movesalong the developing path at substantially the same same speed as themoving electrically conductive surface.

3. A method of developing a latent electrostatic image on a surface of acarrier according to claim 1, and further comprising the additionalsteps of moving cooperating ,squ'eegeeing surfaces into contactwith eachother for receiving the image-bearing carrier, said cooperatingsqueegeeing surfaces moving at substantially the same speed as theimage-bearing carrier moves along the developing path, and moving theimage-bearing carrier between the moving cooperating squeegeeingsurfaces for removing excess liquid from the carrier.

4. A method of developing a latent electrostatic image on a surface of acarrier according to claim 1, and further comprising the additionalsteps of guiding the image-bearing surface of the carrier into contactwith the developing liquid on the electrically conductive surface movingalong the developing path, and guiding the leading edge of the carrieralong the developing path.

5. A method of developing a latent electrostatic image on a surface of acarrier according to claim 4, wherein said image-bearing carrier movesalong the developing path at substantially the same speed as the movingelectrically conductive surface.

6. A method of developing a latent electrostatic image on a surface of acarrier according to claim 5, and further comprising the additionalsteps of moving cooperating squeegeeing surfaces into contact with eachother for receiving 'the image-bearing carrier, said cooperatingsqueegeeing surfaces moving at substantially the same speed as theimage-bearing carrier moves along the developing path, and guiding theimage-bearing carrier between the cooperating squeegeeing surfaces forremoving excess liquid from the carrier.

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